The catalytic hydrogenation of carbon dioxide in the presence of dibutylamine promoted by RuCl3/DPPE has been studied, and the new preparation pathway of N,N-dibutylformylamide has been explored. The effects of temperature, solvent, and the initial pressure of carbon dioxide and hydrogen on the catalytic reaction have been investigated. The turnover number of the reaction was measured by GC and the structure of products was characterized by NMR. The TON (turnover number, mole of product per mole of catalyst) increased with temperature until 120 ℃, then declined. At 4 MPa pressure of CO2, the TON increased with pressure of H2, while at 4 MPa pressure of H2, the TON increased with pressure of CO2 until the pressure of CO2 was up to 6 MPa, then declined. However, at 10 MPa pressure of H2, the TON increased with pressure of CO2. The nonlinear effect of the pressure of CO2 may be due to the reduced stability of dibutylamine to formic acid caused by competition reactions between CO2 and formic acid with dibutylamine. This assumption has been confirmed by the contrast reactions.

Key words: carbon dioxide, RuCl3/DPPE, catalytic hydrogenation, N,N-dibutylformamide, formylation